We work in the language \((\in, \bar\in, <)\), where equality is a defined symbol. \(\in\), \(\bar\in\) and \(<\) are binary predicates, we also define the unary functions \(F\) and \(R\) from these.

We then define the Sasquatch as the largest number \(k\) such that there is some unary formula \(\phi\) in the language \(\{\bar\in,Q\}\) (where \(Q(a,b) \leftrightarrow R(a)=b\)) of quantifier rank \(\leq 12\uparrow\uparrow 12\) such that \(\exists ! a (\phi(a)) \wedge \phi(k)\).